This invention relates to food serving trays and, more particularly, to food serving trays comprising foam.
Polystyrene foam food serving trays are known in the prior art. This body of prior art includes partitioned trays, such as that shown in FIG. 1. Specifically, with reference to FIG. 1, a polystyrene foam tray 1 includes integrally formed bottom walls 2, bounding side walls 3, and a matrix of partitions 4 arranged to define a plurality of compartments 5. The tray 1 can be used to serve simultaneously a plurality of different foods in the compartments 5 with little or no mixing between the different types of foods, as well as, to reduce heat conduction between hot foods and cold foods (thereby preserving the heat of the hot foods).
As more clearly shown in FIG. 1A, the partitions 4 are recessed below the side walls 3. Also, the tray 1 is formed to nest with a similarly formed tray, with the partitions 4 being each formed to encompass an interior volume 6. The partitions 4 of one of the trays 1 can be nestingly received within the interior volumes 6 defined by another of the trays 1 in a nested arrangement. It should be noted that the side walls 3 are formed generally flat between crests 7 of the partitions 4 and top edges 8 of the side walls 3.
In the prior art, foam trays, such as that shown in FIG. 1, are often thermoformed from a single foam sheet. The strength of a resulting tray is generally a function of the shape and structural features of the tray, as well as the amount of foam material used to form the tray. (Assuming no changes in materialsxe2x80x94different materials will, of course, change the strength of the tray.) To vary the strength characteristics of the tray, the amount of foam material can be varied by increasing/decreasing the thickness of the foam sheeting and/or varying the molding characteristics used in forming the foam sheeting (e.g., varying the porosity of the material). In essence, the strength of the tray is a direct function of the weight of the tray. As mentioned above, differences in additives and/or constituent materials will of course have an effect.
To reduce the amount of raw material needed to form a tray, it is desired to enhance the tray""s structural integrity through the formation of structural features which impart additional strength and stability to the tray. In this manner, the amount of raw material necessary to form the constituent foam material can be reduced, and thus there are cost savings, without sacrificing the strength of the tray. As can be appreciated, maximum tray strength is desired to accommodate the loading of food, with minimal chance of tray failure.
It is an object of the subject invention to provide a tray, preferably of polystyrene foam, which is capable of bearing the same amount of weight as prior art trays, but requiring less foam material for formation than in the prior art.
The aforementioned object is met by a food serving tray, formed preferably of polystyrene foam, having a base, which includes bottom walls and partitions, the partitions being interposed between, and connecting, the bottom walls; and side walls extending from, and bounding, the base. The partitions intersect the side walls and subdivide the volume encompassed by the tray into compartments. In accordance with a first aspect of the subject invention, the partitions are formed to be wholly recessed below the side walls, such that the crests of the partitions are spaced from the top edges of the side walls. In addition, a protrusion, preferably directed inwardly, is formed between each intersection defined at the juncture of one of the partitions with one of the side walls, and the top edge of the relevant side wall. Advantageously, the protrusion causes a change in direction of the material forming the side wall, and thereby imparts additional structural rigidity to the tray. With the additionally rigidity, the overall weight of the tray can be reduced, thereby saving on raw material without sacrificing strength of the tray.
Preferably, each of the protrusions is shaped as a step having a relatively planar upwardly facing top surface and a tapered riser surface that follows an arcuate path. More preferably, two step-shaped protrusions are provided above each intersection of partition and side wall, with a larger step protrusion being formed to extend from the crest of the respective partition to a point intermediate the partition and the adjacent top edge of the side wall. The second step-shaped protrusion is smaller in size, extends from the top surface of the larger protrusion, and has its top surface generally coplanar with the top edge of the side wall. The two step configuration defines a tapered socket which can accommodate the finger(s) of a person handling the tray. With the prior art, no tapered socket existed, since the side walls were formed generally flat between the crests of the partitions and the top edges of the side walls.
The coplanarity of the top edges of the side walls and the top surfaces of the second protrusions in effect widens the top edges, thereby providing additional strength. The top edges of the side walls collectively define a flange that encircles the tray. The widening of portions of the flange increases the overall strength of the flange and the tray. In sum, the changes in direction in the side walls provided by the protrusions and the widened flange portions enhance the strength and stability of the tray beyond what is found in the prior art.
In a second aspect of the invention, at least one of the bottom walls of the base is dished so as to be concave and extend upwardly. Advantageously, with load being applied to a bottom wall (such as from food being placed in a compartment), the bottom wall is forced downwardly and bi-axially stressed into a generally flat state which strengthens the respective bottom wall and imparts stability to the overall tray.
These and other features of the invention will be better understood through a study of the following detailed description and accompanying drawings.